Association between histamine-containing mast cells and sensory nerves in the skin and airways of control and capsaicin-treated pigs

Summary The association between mast cells (visualized by routine staining and immunohistochemistry for histamine) and capsaicin-sensitive nerves (containing calcitonin gene-related peptide (CGRP) and substance P (SP)) was studied in the pig. In the 1-ethyl-3(3-diethylaminopropyl)carbodiimide (EDCDI)-fixed skin tissue, histamine-containing mast cells and CGRP/SP-positive nerves were found in close association around blood vessels. In the EDCDI-fixed airway mucosa, only single histamine-containing mast cells were detected. However, many alcian blue-positive mast cells were found, sometimes close to the airway epithelium where CGRP/SP-containing nerve fibres were absent 2 days after systemic capsaicin pretreatment, but no changes in the number and distribution of tissue mast cells, granulocytes or lymphocytes, or the number of blood leukocytes were detected. Local injection of allergen, histamine and capsaicin into the skin of pigs actively sensitized with ascaris antigen caused a rapid light red-flare (vasodilation) reaction. Allergen and histamine, but not capsaicin, also produced plasma protein extravasation. In contrast to the absent flare, the protein extravasation response still occurred in capsaicin-treated pigs. The sensitivity to ascaris antigen was mediated by an IgE-like antibody. We conclude that a functional and morphological relationship exists between histamine-containing mast cells and capsaicin-sensitive sensory nerves in the pig skin. Mast cells and sensory nerves are also found in the airway mucosa and appear to be closely associated with the epithelium.     

Electronmicroscopy of the buccal proper lamina in leukoplakia

The observations included the connective tissue laminae originating from samples of the buccal mucous membrane in leukoplakia. Following fixation and dehydration the materials were embedded in Epon 812, and the electronograms for the evaluation were obtained with the use of a Tesla BS 500 electron microscope. The macrophages were encountered close to the basal membrane in the proper lamina. The space between the basal cells and the macrophages was filled with the connective tissue matrix and numerous collagen fibres, as well as the fibroblast cells. Numerous mast cells, characterized by a specific activity, were noted. Additionally, the proper lamina contained few nerve fibres, usually nonmyelinated. The vascular bed was normal. The electronograms in leukoplakia revealed an active synthesis of the connective tissue matrix and collagen fibres. The marked activity of the mast cells was manifested by a high number of cells containing a relatively differentiated amount of granulation. This might be related to the chronic character of the disease. A significant activity of particular elements of the proper lamina, i.e. the cellular elements, collagen fibres and the connective tissue matrix appears to be characteristic of leukoplakia.     

Mast cells in ulcerative colitis. Quantitative and ultrastructural studies

The changes in the number and ultrastructure of mast cells were studied in 37 colonoscopical biopsies from patients with ulcerative colitis. Changes in the active stage of the disease and during remission were compared. Cell counts were performed on semithin sections stained with Giemsa after osmium tetroxide fixation. This method overcome the uncertain staining found after formalin fixation. Accumulation of mast cells accompanied by intense degranulation was found to be significant in the active stage of the disease. Two forms of degranulation were observed: discharge of the individual granules and protrusion and detachment of the cytoplasmic processes containing granules. The latter was a sign of rapid degranulation, as described earlier in animal experiments. Mast cells were closely associated with capillary blood vessels, Schwann cells, neural fibres, myofibroblasts and collagenous fibres, and were also present between epithelial cells. It is assumed that close topographic contact may also imply a functional correlation.     

Histochemical study of cardiac mast cells degranulation and collagen deposition: interaction with the cathecolaminergic system in the rat

Although their role in the cardiovascular system is still largely unknown, mast cells are present in the myocardium of both experimental animals and humans. Interestingly, cathecolaminergic nerve fibres and mast cells are often described in close morphological and functional interactions in various organs. In the present study we investigated the effects of chronic interference with beta-adrenergic receptors (via either sympathectomy or beta-blockade) on cardiac mast cell morphology/activation and on interstitial collagen deposition. In rats subjected to chemical sympathectomizy with the neurotoxin 6-hydroxydopamine (6-OHDA) we observed a significant increase of mast cell density, and in particular of degranulating mast cells, suggesting a close relationship between the cardiac catecholaminergic system and mast cell activation. In parallel, chronic 6-OHDA treatment was associated with increased collagen deposition. The influence of the beta-adrenergic receptor component was investigated in rats subjected to chronic propranolol administration, that caused a further significant increase in mast cell activation associated with a lower extent of collagen deposition when compared to chemical sympathectomy. These data are the first demonstration of a close relationship between rat cardiac mast cell activation and the catecholaminergic system, with a complex interplay with cardiac collagen deposition. Specifically, abrogation of the cardiac sympathetic efferent drive by chemical sympathectomy causes mast cell activation and interstitial fibrosis, possibly due to the local effects of the neurotoxin 6-hydroxydopamine. In contrast, beta-adrenergic blockade is associated with enhanced mast cell degranulation and a lower extent of collagen deposition in the normal myocardium. In conclusion, cardiac mast cell activation is influenced by beta-adrenergic influences.     

Mast cells in ulcerative colitis

The changes in the number and ultrastruture of mast cells were studied in 37 colonoscopical biopsies from patients with ulcerative colitis. Changes in the active stage of the disease and during remission were compared. Cell counts were performed on semithin sections stained with Giemsa after osmium tetroxide fixation. This method overcome the uncertain staining found after formalin fixation. Accumulation of mast cells accompanied by intense degranulation was found to be significant in the active stage of the disease. Two forms of degranulation were observed: discharge of the individual granules and protrusion and detachment of the cytoplasmic processes containing granules. The latter was a sign of rapid degranulation, as described earlier in animal experiments. Mast cells were closely associated with capillary blood vessels, Schwann cells, neural fibres, myofibroblasts and collagenous fibres, and were also present between epithelial cells. It is assumed that close topographic contact may also imply a functional correlation.     

Mast cells in tumor growth: Angiogenesis,tissue remodelling and immune-modulation

There is a growing acceptance that tumor-infiltrating myeloid cells play an active role in tumor growth and mast cells are one of the earliest cell types to infiltrate developing tumors. Mast cells accumulate at the boundary between healthy tissues and malignancies and are often found in close association with blood vessels within the tumor microenvironment. They express many pro-angiogenic compounds, and may play an early role in angiogenesis within developing tumors. Mast cells also remodel extracellular matrix during wound healing, and this function is subverted in tumor growth, promoting tumor spread and metastasis. In addition, mast cells modulate immune responses by dampening immune rejection or directing immune cell recruitment, depending on local stimuli. In this review, we focus on key roles for mast cells in angiogenesis, tissue remodelling and immune modulation and highlight recent findings on the integral role that mast cells play in tumor growth. New findings suggest that mast cells may serve as a novel therapeutic target for cancer treatment and that inhibiting mast cell function may lead to tumor regression.     

Dynamics of structural parameters of mast cells and accumulation of collagen fibers during radiation-induced pneumosclerosis in rats (a quantitative study)

The methods of stereometry were used to study dynamics of accumulation of collagen fibres and alteration of the number, sizes and state of mast cells of rat lung during the period of 12 months after single local X-irradiation with doses of 10, 14.3 and 20 Gy. A statistically significant correlation between the number of mast cells and spatial density of collagen fibres in the exposed pulmonary tissue was shown. Severity of changes in the structural characteristics of mast cells and the degree of collagen fibres accumulation were a function of radiation dose.     

Occurrence and ultrastructure of mast cells in the hypothalamus of teleost fishes]

From 56 light-, fluorescence- and electronmicroscopically investigated brains of fishes mast cells could be found only in 4 cases. They were concentrated in the meninges of one pike (Esox licius) and in the meninges and at larger blood-vessels of the hypothalamus of 2 trouts (Salmo trutta fario). In the hypothalamus of a carp (Cyprinus carpio) an infiltration of mast cells was detectable in the meninges, at blood-vessels and capillaries, between neuronal and glial fibres and sub- and intraependymaly. Contrary to the pike the granules of the mast cells of the carp show changes, hinting at release of their content. Junctions between mast cells and capillary walls or ependymal cells are characterized by structures indicating an enhanced cytopempsis. The present results are compared with observations on mast cells in the brain and peritoneum of mammals.     

Distribution of Thy-1-like immunoreactivity in normal, sympathetically denervated and grafted mouse irides

The distribution of Thy-1-like immunoreactivity was studied in whole-mounts of adult mouse iris and intraocular iris grafts 4 days and 4 weeks postoperatively. After fixation in picric acid/paraformaldehyde, the irides were incubated with a polyclonal rabbit anti-mouse brain Thy-1 antibody. In the adult mouse iris, a dense network of thin bundles and individual fibres was seen on the dilator plate and in the sphincter. Fluorescence paucities, resembling Schwann cell nuclei, were frequently seen along the bundles. Numerous mast cells, stained specifically with the Thy-1 antibody, were scattered over the entire surface of the iris. The ciliary body contained several brightly fluorescent bundles, and some circularly running individual fibres. In 4-day iris grafts, the Thy-1-like immunoreactivity had disappeared, except in mast cells. After 4 weeks in oculo, a regular plexus of thin fibres had reappeared in the iris grafts. Sympathetic denervation of adult irides did not seem to affect the Thy-1 immunoreactivity in terms of either fluorescence intensity or fibre distribution. The present data suggest a distribution of the glycoprotein Thy-1 along nerve fibres in the iris.     

Distribution of Thy-1-like immunoreactivity in normal,sympathetically denervated and grafted mouse irides

Summary The distribution of Thy-1-like immunoreactivity was studied in whole-mounts of adult mouse iris and intraocular iris grafts 4 days and 4 weeks postoperatively. After fixation in picric acid/paraformaldehyde, the irides were incubated with a polyclonal rabbit anti-mouse brain Thy-1 antibody. In the adult mouse iris, a dense network of thin bundles and individual fibres was seen on the dilator plate and in the sphincter. Fluorescence paucities, resembling Schwann cell nuclei, were frequently seen along the bundles. Numerous mast cells, stained specifically with the Thy-1 antibody, were scattered over the entire surface of the iris. The ciliary body contained several brightly fluorescent bundles, and some circularly running individual fibres. In 4-day iris grafts, the Thy-1-like immunoreactivity had disappeared, except in mast cells. After 4 weeks in oculo, a regular plexus of thin fibres had reappeared in the iris grafts. Sympathetic denervation of adult irides did not seem to affect the Thy-1 immunoreactivity in terms of either fluorescence intensity or fibre distribution. The present data suggest a distribution of the glycoprotein Thy-1 along nerve fibres in the iris.     

Suggestive evidence for a functional unit between mast cells and substance P fibers in the rat diaphragm and mesentery

A close spatial relationship between serotonin-containing mast cells and substance P-containing nerves was shown by immunohistochemistry using a combination of antisera specific for serotonin and substance P. This supports earlier morphological results suggesting an innervation of mast cells and pharmacological studies which postulate an influence of substance P on the release of histamine from mast cells.     

The spatial relationship between the musculature and the NADPH-diaphorase activity, 5-HT and FMRFamide immunoreactivities in redia, cercaria and adult Echinoparyphium aconiatum (Digenea)

The spatial relationship between the musculature and the NADPH-diaphorase (NADPH-d) activity, 5-HT and FMRFamide immunoreactivities in redia, cercaria and adult Echinoparyphium aconiatum was studied using scanning electron microscopy (SEM), NADPH-d histochemistry, immunocytochemistry, and confocal scanning laser microscopy (CSLM). TRITC-conjugated phalloidin was used to stain the musculature. Staining for NADPH-d was observed in the central (CNS) and peripheral nervous system (PNS) of all three stages. NADPH-d positive nerves occurred very close to muscle fibres. 5-HT-immunoreactive (5-HT-IR) nerve cells and fibres occurred in the CNS and PNS and close to muscle fibres. FMRFamide-IR nerve fibres were observed in the CNS and PNS of adult worms. This is the first time, the presence of the NADPH-d has been demonstrated in the larval as well as the adult stages of a fluke.     

Immunohistochemical analysis of substance P containing nerve fibres and their contacts with mast cells in the diabetic rat's tongue

Sensory neuropathy is common symptom of the diabetes mellitus and the prevalence of oral lesions is higher in diabetic patients. The distribution of substance P was studied immunohistochemically in streptozotocin induced diabetic rat's tongue. The morphological association of sensory nerves (substance P immunoreactive) with mast cells (nerve fibre-mast cell contact) was monitored. The substance P nerve fibre mast cell contacts were very scanty in control tongue. The number of substance P nerve terminals and mast cells was significantly increased (p < 0.05) in diabetes mellitus after 4 weeks of the treatment compared with the control tongue. The number of mast cell nerve contacts was even more significantly increased (p < 0.001) in diabetes. The distance between nerve fibres and mast cells was about 1 mm and very often less than 200 nm. In some instances, the mast cells were degranulated in the vicinity to nerve fibres. Increased number of mast cell nerve contacts in neurogenic inflammation might cause vasoconstriction and lesions of the oral mucosa, so some disorders such lichen planus, leukoplakia and cancer might frequently develop in diabetes mellitus.     

Circadian rhythm of the thyroid mast cells in untreated and methylthiouracil-treated rats

Recent investigation have shown that mast cells of the rat thyroid participate in the regulation of thyroid function. Serotonin released from the mast cells influenced by thyrotropin promotes iodothyronine secretion by its effect on the thyroid follicle cells. The present histophysiological studies on the circadian rhythm in the normal rat thyroid reveal a close correlation between the number of the thyroid mast cells and the thyroid function. It has been shown that in the morning, when thyroid function is decreased, the number of the mast cells is low, but at noon it shows an increase an then is highest in the evening, when the thyroid activity is most intense. This phenomenon suggests a relationship between the mast cell function and the thyroid feedback mechanism. In methylthiouracil-treated rats inhibition of the thyroid iodothyronine production and change of the feedback mechanism function induce development of a hypertrophic goitre in which degranulation of the mast cells accompanied by release of their bioamines induce dilatation of blood vessels and increase in the thyroid blood flow. Simultaneously the circadian rhythm of the thyroid mast cell occurrence is changed, i.e. their number found in the morning gradually decreases by the evening.     

Mast and enterochromaffin-like cells of the gastric mucosa]

An attempt has been made to reveal simultaneously both mast and ECL cells in the fundic mucosa of some laboratory animals and man. In Bouin fluid fixed specimens, toluidine blue pH 5.0 and alcian blue pH 1.0 failed to reveal mucosal mast cells in rats and mice only. In those animals mucosal mast cells became demonstrable in Carnoy fluid fixed tissues after staining with alcian blue pH 1.0. A double staining technique has been applied using Grimelius silver method followed by staining either with toluidine blue after acid hydrolysis or with alcian blue. Both mast and ECL cells became visible showing here and there their close arrangement. The latter might be a point for some functional relations between both cell types.     

Ultrastructural cytochemical, immunocytochemical and in situ hybridization methods with polyuridine probes detect mRNA in human mast cell granules

Mature human mast cells are classical secretory cells that are filled with secretory-storage granules but are poorly endowed with visible free or membrane-bound cytoplasmic ribosomes. We recently reported close associations of ribosomes and various components essential to RNA metabolism in and close to human mast cell granules using multiple ultrastructural imaging methods. In view of these findings and an increased awareness of RNA sorting and localization to specific subcellular sites and organelles, we used human mast cells purified from non-tumour portions of lung samples resected at surgery for carcinoma and ultrastructural methods to investigate this further. Poly(U) probes were used to detect direct en grid binding, and radiolabelled as well as non-radiolabelled poly(U) probes were used in in situ hybridization protocols to detect poly(A)-positive pre-mRNA and mRNA in nuclear, cytoplasmic and granular compartments of mature human mast cells. Negative controls verified specificity of label; expected nuclear and cytoplasmic locations of poly(A)-positive RNA served as positive controls for each sample. These findings lend support to the hypothesis that site-specific synthesis in secretory-storage granules may occur in secretory cells.     

Suggestive evidence for a functional unit between mast cells and substance P fibers in the rat diaphragm and mesentery

Summary A close spatial relationship between serotonin-containing mast cells and substance P-containing nerves was shown by immunohistochemistry using a combination of antisera specific for serotonin and substance P. This supports earlier morphological results suggesting an innervation of mast cells and pharmacological studies which postulate an influence of substance P on the release of histamine from mast cells.International Research Fellow, awarded by Fogarty International Center, Fellowship number 1 FO5 TWO 3293-01 BI     

Endogenous peroxidase in mast cells localized with a semipermeable membrane technique

Synopsis Hamster mast cells have been found to give strong peroxidatic reactions at pH 5, 7.5 and 10 when sections of skeletal muscle are incubated for 2.5 h in the dark at room temperature on semipermeable membranes covering a gelled incubation medium consisting of 0.01% hydrogen peroxide, 5.5 mM diaminobenzidine and 1.36% agar dissolved in Universal buffer. The techniques is very efficient: with it, all mast cells react in marked contrast to the negative reaction they usually give with conventional techniques.The peroxidatic reactions are abolished if tissues are perfused beforehand with either aminotriazole or KCN but not if these inhibitors are incorporated in the gelled incubation medium. This and other evidence suggests that the mast cell reactions are not due to either catalase or haemoglobin adsorbed onto mast cell granules from lysed red blood cells.Skeletal muscle fibres do not exhibit any visible-peroxidase activity with the membrane technique.     

New approaches for the analysis of mast cell maturation, heterogeneity, and function

Mast cells are regarded as potentially critical participants in a wide variety of important biological processes. Yet it has been difficult to ascertain the precise contribution of mast cells to many of these reactions. In part, this reflects recognition that different populations of mast cells may vary in phenotype and therefore may express different functions. Another problem has been the lack of suitable model systems for identifying and quantitating the mast cell's unique roles in biological processes in intact animals. This review will outline the development of promising new approaches for analyzing mouse mast cell differentiation and phenotypic heterogeneity and for studying the roles of mast cells in vivo.     

Functional morphology of the adrenergic innervation and adrenocontaining structures of the lymphoid organs

Topography of adrenergic neural fibres and adrenodependent structures in lymphoid organs of some mammals (rat, cat, dog, guinea-pig, golden hamster) has been studied by means of Falck's method with other histochemical methods applied simultaneously. In thymus, spleen, tonsils, lymph nodes and appendix adrenergic innervation is performed at the expense of adventitial vascular plexus and some neural fibres directed towards the organs' parenchyma. In the parenchyma of the lymphoid organs some fluorescent interfollicular macrophages and intrafollicular cells with serotonin and catecholamines in their cytoplasm were detected spectroscopically. These two types of cells respond differently to increasing amount of free amines in the organism. Orthochromic mast cells and elastic fibres also possess fluoresent properties which are connected with the presence of serotonin and catecholamines in the lymphoid organs.